Li Yifei certainly knew what Aoki Reiko was doing; in fact, he had wanted to do the same earlier, but if he said it out loud, it would seem like he cared about Aoki Reiko. If he showed concern for Aoki Reiko, and if that made her emotional, she might speak in favor of Li Yifei or intentionally hide something when facing the police later. That could easily get her into big trouble, so Li Yifei could only let her figure it out on her own.
Moreover, when they surfaced again, Li Yifei spoke discontentedly, "Don't stick your hand inside my clothes."
Seeing Li Yifei's dissatisfaction, Aoki Reiko's mood improved drastically. This was her chance to get back at him. He had taken her hostage and made her freeze like this; what other way could she retaliate against Li Yifei?
"If you don't let me reach in, I'll do it anyway." At that moment, Aoki Reiko even started to pull up Li Yifei's clothes.
"If you keep messing around, believe it or not, I'll throw you over here right now."